A method and system of post-processing of sensing data generated by a medical device that includes transmitting a plurality of stored sensing data generated by the medical device to an access device, the stored sensing data including sensed atrial events and sensed ventricular events. The access device determines, in response to the transmitted data, instances where the medical device identified a cardiac event being detected in response to the sensing data, and determines, in response to the transmitted sensing data, whether one of the sensed ventricular events and the sensed atrial events is initiating conduction of a heart associated with the stored sensing data.
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1. A method of post-processing of sensing data generated by and stored within an implantable medical device, comprising: receiving the sensing data from the implantable medical device with an external access device, wherein the sensing data includes sensed atrial events and sensed ventricular events; determining, with the external access device, in response to the received data, instances where the implantable medical device identified a cardiac event being detected in response to the sensing data; and determining, with the external access device, in response to the received sensing data, which one of the atria or the ventricles of a heart associated with the sensing data initiated conduction of the heart by at least determining which one of the sensed ventricular events or the sensed atrial events initiated conduction of the heart, wherein determining which one of the sensed ventricular events or the sensed atrial events initiated conduction of the heart comprises: identifying a spatial reference point within a portion of the received sensing data comprising sensed atrial and ventricular events from a plurality of cardiac cycles, wherein the spatial reference point is an identified cardiac interval within the received sensing data; generating a window around the spatial reference point, the window comprising a subset of the sensed ventricular events, in response to the spatial reference point, wherein the subset of the sensed ventricular events comprises a plurality of the sensed ventricular events; determining numbers of the sensed atrial events between the ventricular events within the subset of sensed ventricular events; and determining which one of the sensed ventricular events or the sensed atrial events initiated conduction of the heart based on the numbers of the sensed atrial events between the ventricular events within the subset of sensed ventricular events.
A method post-processes heart sensor data from an implanted medical device using an external device. The external device receives atrial and ventricular event data from the implanted device. It identifies where the implanted device detected a cardiac event. It then determines if the atria or ventricles initiated heart conduction. This is done by finding which of the atrial or ventricular events started the conduction. It involves identifying a spatial reference point in the data comprising atrial and ventricular events across several heart cycles, this spatial reference point being a cardiac interval. A window is created around the reference point, containing a subset of ventricular events. The number of atrial events between the ventricular events within this subset are counted. Finally, atrial or ventricular initiation is determined based on these atrial event counts between the ventricular events.
2. The method of claim 1 , wherein identifying a spatial reference point comprises determining, starting with a last ventricular sense event associated with a cardiac event being detected, when a predetermined number of sequential adjacent intervals occurring prior to the last ventricular sense event are greater than an onset threshold.
The method of post-processing heart sensor data, as described previously, identifies a spatial reference point by determining, starting from the last detected ventricular event associated with the cardiac event, when a certain number of sequential intervals before that ventricular event are larger than a threshold. This means it looks backward from the end of the event for increasing interval lengths to pinpoint a start-of-event reference point.
3. The method of claim 2 , further comprising: determining a first median of first sensing data of the plurality of received sensing data occurring just prior to the cardiac event being detected; determining a second median of second sensing data of the plurality of received sensing data occurring prior to a number of intervals to detection associated with the cardiac event being detected; and determining a difference between the first median and the second median, wherein an abrupt onset is determined in response to the difference being greater than a predetermined threshold, wherein the onset threshold is set as a sum of the first median and a portion of the determined difference.
The method of post-processing heart sensor data, as described previously, further determines a first median of sensing data shortly before the detected cardiac event. It also determines a second median of sensing data before a certain number of intervals leading up to the cardiac event detection. The difference between these medians is calculated. An abrupt onset of the cardiac event is determined if this difference exceeds a threshold. The onset threshold is set as the sum of the first median and a portion of the calculated difference. This method helps in dynamically setting a threshold based on recent heart activity.
4. The method of claim 1 , wherein determining numbers of the sensed atrial events between the ventricular events within the subset of sensed ventricular events and determining which one of the sensed ventricular events of the sensed atrial events initiated conduction of the heart based on the numbers or the sensed atrial events between the ventricular events within the subset of sensed ventricular events comprises: determining a number of sensed atrial events between each of a plurality of adjacent pairs of the sensed ventricular events within the subset of sensed ventricular events within the window, wherein the sensed atrial events are determined to be initiating the conduction in response to no sensed atrial events occurring between more than one of the adjacent pairs and only one sensed atrial event occurring between each of the other of the adjacent pairs of the sensed ventricular events within the window, and the sensed ventricular events are determined to be initiating conduction in response to no sensed atrial events occurring between only one of the adjacent pairs and only one sensed atrial event occurring between each of the other of the adjacent pairs of the sensed ventricular events within the window.
In the method of post-processing heart sensor data, as described previously, determining the number of atrial events between ventricular events within the ventricular subset, and determining which of the atrial or ventricular events initiated conduction based on these counts, involves the following: The number of atrial events is counted between each adjacent pair of ventricular events within the window. Atrial initiation is determined if there are no atrial events between more than one adjacent pair, and only one atrial event between all the other adjacent pairs. Ventricular initiation is determined if there are no atrial events between only one adjacent pair, and only one atrial event between all the other adjacent pairs.
5. A system for post-processing of sensing data associated with identification of a cardiac event, comprising: an implantable medical device generating and storing a plurality of sensing data, wherein the sensing data includes sensed atrial events and sensed ventricular events; an access device located externally from the implantable medical device; and an interface for receiving the sensing data from the implantable medical device with the external access device, wherein the external access device determines, in response to the received data, instances where the medical device identified a cardiac event being detected in response to the sensing data, and which one of the atria or the ventricles of a heart associated with the sensing data initiated conduction of the heart by at least determining which one of the sensed ventricular events and the sensed atrial events is initiating conduction of the heart, wherein the access device: identifies a spatial reference point within a portion of the received sensing data comprising sensed atrial and ventricular events from a plurality of cardiac cycles; generates a window around the spatial reference point, the window comprising a subset of the sensed ventricular events, in response to the spatial reference point, wherein the subset of the sensed ventricular events comprises a plurality of the sensed ventricular events, and wherein the spatial reference point is an identified cardiac interval within the received sensing data; determines numbers of the sensed atrial events between the ventricular events within the subset of sensed ventricular events; and determines which one of the sensed ventricular events or the sensed atrial events initiated conduction of the heart based on the numbers of the sensed atrial events between the ventricular events within the subset of sensed ventricular events.
A system post-processes heart sensing data to identify cardiac events. It includes an implanted medical device storing atrial and ventricular event data. An external access device receives this data. The external device identifies instances where the implanted device detected a cardiac event, and determines if the atria or ventricles initiated the heart's conduction by finding which atrial or ventricular events initiated conduction. To do this, the access device identifies a spatial reference point in the received sensing data, which comprises atrial and ventricular events across multiple cardiac cycles, the spatial reference point being a cardiac interval. It generates a window around this point containing a subset of ventricular events. Then, it counts the atrial events between ventricular events within the subset and determines if the atria or ventricles initiated the conduction based on the counts.
6. The system of claim 5 , wherein the external access device identifies a spatial reference point by determining, starting with a last ventricular sense event associated with a cardiac event being detected, when a predetermined number of sequential adjacent intervals occurring prior to the last ventricular sense event are greater than an onset threshold.
The system for post-processing heart sensing data, as described previously, identifies a spatial reference point by starting from the last detected ventricular event associated with the cardiac event, and determining when a predetermined number of sequential adjacent intervals before that ventricular event are greater than an onset threshold. This effectively looks backwards from the end of the detected event to identify a specific point representing the start or onset of the event based on interval changes.
7. The system of claim 6 , wherein the external access device determines a first median of first sensing data of the plurality of received sensing data occurring just prior to the cardiac event being detected, a second median of second sensing data of the plurality of received sensing data occurring prior to a number of intervals to detection associated with the cardiac event being detected, and a difference between the first median and the second median, wherein an abrupt onset is determined in response to the difference being greater than a predetermined threshold, and wherein the onset threshold is set as a sum of the first median and a portion of the determined difference.
In the system for post-processing heart sensing data, as described previously, the external access device determines a first median of sensing data shortly before the detected cardiac event and a second median of sensing data before a specific number of intervals leading up to the detection. It then calculates the difference between the medians. An abrupt onset of the cardiac event is detected if the difference exceeds a threshold. The onset threshold is set as the sum of the first median and a fraction of the calculated difference, thereby dynamically setting a detection threshold.
8. The system of claim 5 , wherein, to determine numbers of the sensed atrial events between the ventricular events within the subset of sensed ventricular events and determine which one of the sensed ventricular events or the sensed atrial events initiated conduction of the heart based on the numbers of the sensed atrial events between the ventricular events within the subset of sensed ventricular events, the external access device: determines a number of sensed atrial events between each of a plurality of adjacent pairs of the sensed ventricular events within the subset of sensed ventricular events within the window, wherein the sensed atrial events are determined to be initiating the conduction in response to no sensed atrial events occurring between more than one of the adjacent pairs and only one sensed atrial event occurring between each of the other of the adjacent pairs of the sensed ventricular events within the window, and the sensed ventricular events are determined to be initiating conduction in response to no sensed atrial events occurring between only one of the adjacent pairs and only one sensed atrial event occurring between each of the other of the adjacent pairs of the sensed ventricular events within the window.
In the system for post-processing heart sensing data, as described previously, to determine the number of atrial events between ventricular events and identify the conduction initiator, the external access device counts the number of atrial events between each adjacent pair of ventricular events within the defined window. Atrial initiation is determined if no atrial events occur between more than one adjacent pair, while exactly one atrial event occurs between all other adjacent pairs. Conversely, ventricular initiation is determined if no atrial events occur between only one adjacent pair, while exactly one atrial event occurs between all other adjacent pairs.
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November 28, 2006
September 10, 2013
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